The present invention relates to water purification and filtration systems and, in particular, to a system including an iodine resin purification bed.
Along with expanding populations and industrialization has come an ever expanding problem of water pollution, either by way of chemical or microbial contaminants (i.e. bacterial, viral or parasitic). Natural sources of potable drinkable water are proportionately decreasing, thus requiring various processing treatments to make the water consumable.
Varieties of techniques have been developed in the latter regard at the bulk treatment levels for large populations, as well as for small volumes for an individual or household. These methodologies may include varieties of mechanical treatment systems and/or chemical treatments, but which systems suffer from various shortcomings. For example, distillation systems, while producing substantially contaminant free re-constituted water, does so at the loss of naturally occurring minerals. These systems are also slow and require large amounts of energy. Chemical treatment systems, similarly, are costly and/or leave residual tastes in the treated water.
Filtration systems and, in particular, granulated active carbon (GAC) systems, otherwise, economically remove a wide variety of relatively small contaminants. The beds do not however remove various viral and bacterial contaminants which can collect and grow within the carbon beds, thus necessitating the re-charging of the beds or costly treatment thereof to remove the undesired contaminants. Agencies responsible for large installations, as well as approval regulators for smaller installations, have accordingly begun to withhold approval for such systems.
One approach in the small volume treatment market has been to interject, upstream of the GAC, a purification element for devitalizing (e.g. sterilizing or killing) specific viruses and bacteria, prior to entering the bed. Such purification elements may also be mounted downstream of the bed to prevent reverse contamination. One cartridge system known to Applicants utilizing an iodine resin purification bed is sold by Water Technologies, Inc., Plymouth, Minn.
The cartridges of this system particularly includes a GAC bed and a co-axially aligned resin bed of equal cross-sectional flow area containing polystyrene beads to which are bonded iodine molecules. This resin is described in U.S. Pat. No. 4,238,477 and has proven effective in destroying the viral, bacterial and parasitic contaminants, when deposited to a bed depth sufficient to provide proper contact time between the resin and water.
Although effective in practice, the foregoing cartridges have proven to be economically rather expensive to produce, due to the use of excessive amounts of resin. That is, the resin bed portion of the cartridges have been constructed oversize relative to the life of the GAC bed, in lieu of adjusting the cartridge housing configuration. Although, too, a certain contact time is required between the water and purification bed to assure removal of undesired contaminants, presently available cartridges only provide a bed depth of approximately 3/4 inches.
Applicants have determined, however, that smaller volumes of purification media can be used without effecting the cartridge properties. In particular, the cross-sectional flow area of the purification bed need not be the same as the adjacent GAC bed. The length of the purification bed can also be increased without constricting throughout flow, among other improvements which better match the effective resin life and volume to that of the GAC bed.
In appreciation of the foregoing, Applicants have developed various systems, and purification/filtration cartridges and assemblies which are more economical to manufacture via a lengthening and downsizing of the volume of iodine purification resin material, while still maintaining proper contact time between the resin and water and without effecting the throughput rate.